Left-digit effect
£19.99 feels meaningfully cheaper than £20 because the left-most digit dominates.
Where it applies
Two of the eight page areas.
How to use it
Four ways to put it to work.
- Use just-below prices where the left digit drops, such as £19.99 rather than £20.00.
- Apply them mainly on price-sensitive lines.
- Expect a small lift, not a large one.
- Treat the advice to use round prices for premium, gift and emotional purchases as unproven.
What the research found
Just-below prices tend to increase purchases, but the effect is small and varies widely.
A one-cent rise from a 99 ending cuts demand like a 20-cent rise.
A preregistered meta-analysis of 69 studies by Troll and colleagues found just-below prices tend to increase purchases, but effects were small, varied widely and shrank after correcting for publication bias. In US scanner data covering 3,500 products in 25 chains, Strulov-Shlain found a one-cent rise from a 99 ending cut demand like a rise of more than 20 cents. Two later preregistered experiments found just-below prices improved price image but did not reliably change purchase intention.
Key research
Four sources, each checked.
Last reviewed
Thomas & Morwitz (2005) Penny Wise and Pound Foolish: The Left-Digit Effect in Price Cognition J. Consumer Research Read the source Troll, Frankenbach, Friese & Loschelder (2024)Meta-analysis A meta-analysis on the effects of just-below versus round prices J. Consumer Psychology Read the source Strulov-Shlain (2023) More Than a Penny's Worth: Left-Digit Bias and Firm Pricing Review of Economic Studies Read the source Escher, Troll, Henjes & Loschelder (2026) How consumers evaluated precise, just-below, and round prices: evidence from two high-powered, preregistered experiments Frontiers in Behavioral Economics Read the source